Today, we turn thought into diamonds. The
University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
Hard as diamond! Clear as
diamond! Diamond is a powerful metaphor for
perfection we rarely achieve on this imperfect
earth. And it's a material that lives up to its
reputation. It's the hardest natural material. It's
the best natural conductor of heat -- five times
better than copper or silver. Yet it's also an
electric insulator.
Diamond is transparent as nothing else is. Glass
and water transmit only visible light. Diamond is
transparent on both sides of the visible range. It
will let ultraviolet and infrared, as well as
X-rays, through. Diamond is a material we'd dearly
love to use in all sorts of processes.
But a natural diamond, even the size of peanut, is
rare and hopelessly expensive. It derives part of
its beauty from slight impurities. We have powerful
cause to make our own diamonds. Good homemade
diamonds would be far more valuable in human terms
than anything Amsterdam offers.
In 1954, people at GE learned to make diamonds by
heating and compressing graphite. Today, that's
done at 2700 degrees Fahrenheit and a million
pounds per square inch. We can create a limitless
supply of diamonds. But the result has drawbacks.
It isn't very pure. It's made from many small
crystals, not one big one. It costs a dollar a
carat, and it's widely used to make abrasives.
Now the Japanese have created a new process. It's
called CVD, for Chemical Vapor Deposition. They
condense carbon vapor on a plate in the presence of
atomic hydrogen. It's still a grainy material, but
it's pretty pure. You can make it into sheets as
large as 1-1/2 inches by 12 inches. The problem
with the process is its cost -- around $100 a
carat. The expense doesn't come from the process
itself. It comes from the cost of breaking hydrogen
molecules into atoms.
The new process doesn't put the problem of making
diamonds to rest. But it opens a window into the
imagination. Now we can make diamonds without going
to science-fiction pressures. The process gives us
hope. Now we call on a new science called epitaxy.
Epitaxy means growing single crystals of a material
on top of another material. That's one way to make
semiconductors. We've begun learning to deposit
carbon vapor into pure crystals.
Diamonds have driven the imagination for centuries,
but they're doing it today as never before. Now
they promise windows that can't be clouded, glasses
that can't be scratched, computer chips that won't
melt, and much more. But the promise isn't free. It
depends on our making full use of our inventive
minds.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
